ECS 5365 Invited Lecture Overview of Digital Subscriber

ECS 5365 Invited Lecture Overview of Digital Subscriber Line z. James Kershaw z Transmission Systems Division z NEC Australia Pty Ltd z http: //www. nec. com. au

Agenda z. What is Digital Subscriber Line? z. Standardization z. DSL Architecture z. Technical Issues z. Typical Applications

Digital Subscriber Line z. Modem based Access Technology z. Existing Subscriber Infrastructure z. Higher Speed Connections z. Pair Gain Capability

Advantages of DSL z. Point to Point Connection y. Dedicated bandwidth y. Inherent Security z. Existing Infrastructure y. Reduced roll-out costs z. Cheaper Operating Costs

Types of DSL Performance y. ISDN y. IDSL y. MDSL y. SDSL y. HDSL - ISDN DSL - Multi-rate DSL - Single-loop DSL - High-speed DSL y. SHDSL - Single Pair HDSL y. RADSL - Rate Adaptive ADSL y. ADSL - Asymmetric DSL y. VDSL -Very-high-speed DSL

Standardization z. What needs to be standardized? z. Who is involved with Standardization? z. What standards exist?

What needs to be standardized? z. Physical Interfaces z. Electrical Interfaces z. Link Layer Behaviour z. Network Layer Behaviour z. Signaling and Negotiation z. Test Procedures z. Electrical Compatibility

Who is Involved z. National Bodies eg. ANSI z. Regional Bodies eg. ETSI z. International Bodies eg, ITU-T, IETF z. Special Interest Groups eg. ADSLF, ATMF

International DSL Standards y. ITU-T Standards ÞG. 991 (G. hdsl) - T 1/E 1 symmetric ÞG. 991. 2 (G. shdsl) - under study ÞG. 992. 1(G. dmt) - 16 Mbit/s down, 1. 1 Kbit/s up • Annex A - ADSL over POTS • Annex B - ADSL over ISDN • Annex C - ADSL over POTS, suitable for Japan ÞG. 992. 2 (G. lite) - 1500/640 Kbit/s ÞG. 993 (G. vdsl) - under study ÞG. 994. 1 (G. handshake) - DSL Negotiation

National/Regional Standards z. American National Standards Institute yeg T 1. 413 G. 992. 1, TR 28 = HDSL z. European Telecommunications Standardization Institute yeg ETR 328 ADSL, TS 101 135 TR 28

Special Interest Groups z. ADSL Forum y. System Architecture and Interoperability y. Creates Technical Reports z. ATM Forum y. ADSL is yet another physical layer for ATM y. Creates Industry Specifications z. Others

DSL Architecture z. Reference Architecture z. Medium z. Modulation z. Spectrum z. Typical Configurations

Reference Architecture (ADSLF) A 11 A 10 Service Provider V Regional Broadband Network U Access Node T Network Termination (B-NT) S Customer Premises Network Customer Premises Equipment Core Network A 11, A 10 are from DAVIC V, U, T, S are from ITU-T

DSL Medium z. Twisted Pair y. Two Wire ÞADSL, IDSL, SDSL, HDSL 2, VDSL y. Four Wire ÞHDSL y. Six Wire ÞHDSL

Modulation y. Carrierless Amplitude-Phase Modulation (CAP) y. Discrete Multi-Tone (DMT) y 4 B 3 T - 16 codes mapped onto 27 y 2 B 1 Q - 4 codes mapped onto 4 y. Others 4 B 3 T 2 B 1 Q

Frequency Spectrum G. 992. 1 DMT 25 Channels POT Upstream S <255 Channels Downstream y 16 bits/symbol y 4 Kbaud/tone y 64 Kbit/s/tone 4. 3125 k. Hz 4 26 Upstream Rates: 16 - 1600 kbit/s Downstream Rates: 32 - 16320 kbit/s 1104 f(k. Hz)

Technical Problems z. Cross Talk z. Interference y. Impulse Noise y. Radio Noise z. Line Impairments

Cross Talk z Near End & Far End z Solutions y. Increase with Frequency y. Decrease with Separation y. NEXT is the biggest problem z Increasing Power doesn’t help!! y. Reduce Coupled Power ÞReduced Rates ÞReduced Reach y. Frequency Separation ÞSpectral Masking y. Spatial Separation ÞAsymmetric Rates NEXT FEXT

Impulse Noise z Noise Sources y. Local in Time y. Spread in Frequency ye. g. from POTS signaling z Solution (for G. 992. 1) y. Add Redundancy ÞForward Error Correction ÞRead-Solomon Coding ÞTrellis Coding y. Spread the Signal ÞVarious Interleave Depths • 1 256 (x 250 ms frames) • 250 ms 64 ms Delay y. Increase Received Power ÞReduce Reach

Radio Noise z Noise Sources y. Local in Frequency y. Spread in Time yeg Radio Stations yeg Other Transmitters z Solutions y. Spectrum Negotiation Þie During Start-up y. Dynamic Rate Adaptation y. Increase Received Power ÞReduced Reach

Line Impairments z Bridge Taps y. Cause Attenuation z Loading Coils y. Block higher frequencies z Split Pairs y. Electrical Imbalances z Impedance Imbalance y. Increases Noise z Solutions y. Select good Lines y. Reduce Reach y. Spectrum Negotiation

Typical Applications z Digital Loop Carrier y. Scarcity of good pairs y. Pair Gain with virtual lines z High Speed Modems z WAN Access y. Branch offices y. Small Campuses y. ATM, Frame Relay y. FDDI, SMDS y. Business Data Applications z PABX access y. Branch Offices y. Residential Data Applications y. Small Campuses y. T 1/DS 1, E 1

Emerging Technologies y. Voice over DSL (Vo. DSL) ÞBroadband Loop Emulation Service (BLES) ÞPABX Extension ÞVoice over Multi Service Data Services (VMSDS) y. Symmetrical DSL ÞSHDSL, HDSL 2, VDSL y. Network Management ÞIntegrated ILEC, CLEC, ISP ÞOut of Box Plug and Play

Vo. DSL Issues y. Which Service Types? ÞPOTS, CCS, CLASS, CENTREX, IN, AIN y. Delay Limits? ÞInterleaving, ISDN time-out risk y. Lifeline Service? ÞRemote Power Feed y. Signaling? y. Network Interface? ÞPSTN (V 5. 1, V 5. 2, GR. 303, TR. 008) ÞB-ISDN (Circuit Emulation)

Market Status y. Systems Þ 53 Announced Trials Þ 80 Service Deployments y. Market Information Þ 35 million homes passed Þ 100 K installed modems Þ 800 M installed copper pairs Þ 170 ISPs offering DSL in USA y 70% of World does NOT have Cu-pair Þ? ? Mobile Technology ? ?

Supercom’ 99 y. ADSL Interoperability Stand Þ 14 DSLAM Vendors Þ 25 CPE Vendors Þ~35 Market Announcements y~25 -30 CPE Vendors displaying y~15 -20 DSLAM Vendors displaying y~10 ISP’s displaying “Everyone was showing Video”

More Information z. ADSL Forum y. Moving to a generic focus (DSL Forum) yhttp: //www. adsl. com z. Technology overview pages yhttp: //www. aspergantis. com/adsl/index. htm